I-88, I-290, I-294, US 20, IL 38, and IL 64Hillside, IL

formerly "The Hillside Strangler"

Overview: This interchange is another from the Chicagoland area that involves the intersection of two highways spread over a long distance (see also I-88 and I-355 just west of here). Here, I-294 runs north-south as the Tri-State Tollway (which, incidentally, never leaves Illinois). I-290 enters from the northwest, and after its intersection with US 20 and IL 64, runs southward along the I-294 corridor. At the main part of the interchange, it turns to the east and heads towards downtown Chicago. I-88, which is known as the East-West Tollway, enters from the southeast and ends at I-290. Another small freeway connects I-88 and I-294, south of the bulk of the interchange; this is unnumbered, but is considered a spur of I-88.
A number of local roads and state routes also run through this junction. At the north end are US 20 and IL 64. IL 64 runs east-west through the modified cloverleaf where I-290 and I-294 part (this is exits 13A and 13B from I-290); US 20 comes into this part of the junction from the southeast, and leaves multiplexed with I-290. Moving southward, there is a cloverleaf on I-290; this is exits 14A and 14B. The crossroad here is Saint Charles Road. Exit 15 on I-290 is for I-294 and I-88, forming the triangle of roads east of I-294. IL 56 runs northeast-southwest through the middle of this triangle, but never plays any direct part in the interchange. The next major east-west road is IL 38, which forms a half-cloverleaf with I-294. There is also a cloverleaf between IL 38 and York Road, west of I-88; this also has no direct bearing on the interchange itself. Finally, the last east-west road is Cermak Road; this passes just south of the mainline toll plaza on I-294, and two loop ramps connect it to I-294.
To take a closer look at the interchange, we'll do an enlarged view and a description for each of the four major parts.

I-290, I-294, US 20, and IL 64: This intersection forms the northernmost point on the entire junction. The majority of the ramps are devoted to transferring traffic between I-290, US 20, and IL 64; part of also allows traffic to use the "U-turn" movements (SB->NB) between I-290 and I-294.
Ignoring the ramps to and from I-294, there is basically a 3/4-cloverleaf here between I-290 and IL 64. Movements from IL 64 EB to I-290 WB, and I-290 EB to IL 64 WB, are unavailable here; they can be made by using IL 83, a mile and a half or so to the west. All of the ramps to and from the south form a standard half-cloverleaf, with one exception: the I-290 northbound (actually westbound) ramp to IL 64 EB gets cut off by US 20 EB, and traffic can use it only to get to US 20. Two more ramps carry the mainline US 20 designation from US 20 to its multiplex with I-290, and each one connects to IL 64 to the east as well. Interestingly enough, there is no connection from US 20 WB to IL 64 WB, as well as missing connections for the two WB->EB movements; these are available by using local streets to the east.
Two ramps also connect I-294 to other highway. The SB offramp from I-294 crosses over the I-290 NB offramp to US 20, and then joins I-290 NB; this could also be used to access IL 64 WB (via a loop ramp) or, if needed, I-290 SB (via both loop ramps), but I don't think either of these are signed (the latter especially). Another connection is available from I-294 SB to I-290 SB/EB further south, so this connection would only be used by I-294 traffic bound for Saint Charles Road. (see next photo) The final ramp here is an onramp to I-294 northbound, which is available from both directions on US 20 (and from IL 64 EB, consequently) but not from IL 64 WB. It could aso be used as a connection from I-290 NB to I-294 NB, for traffic coming from Saint Charles Road.

I-290 and Saint Charles Road: Exit 14 on I-290 is a fairly straightforward cloverleaf; I just included the close-up for the sake of being complete. Notice how I-294 barely skirts the edge of this interchange, without any connections to the local streets; it actually passes under the ends of two of the ramps. Despite the lack of direct ramps, access to I-294 is available to and from all directions. Traffic going between Saint Charles Road and I-294 to the south can simply use I-290, down to the point where it crosses under I-294 (see next photo); traffic between here and I-294 to the north can use ramps at the US 20 interchange (see previous photo); these are available, while not exactly convenient.

I-88, I-290, and I-294: Here's the bulk of the interchange. I-290 enters from the northwest, crosses under I-88, and leaves to the east; I-88 comes in from the southwest. The intersection of I-290 and I-294 is pretty simple; ramps are available to allow traffic to make the same-direction movements only (NB to NB, SB to SB). The ramp from I-294 SB to I-290 EB is well-built, so that traffic doesn't have to slow all the way down to 20 or 30 mph to get around a loop ramp; its counterpart, I-294 NB to I-290 WB, does not have this advantage. Further east, I-290 and I-88 meet in a simple directional split. This is the eastern terminus of I-88. Note the offramp from I-88 EB, just before it merges with I-290; this ramp, and the one from the I-290 EB lanes, is an exit ramp for the next exit to the east.
The junction between I-294 and I-88 is a "half-stack", with three levels; only one set of left turn movements is available. It does have some variations from the typical design, however. NB on I-294, there is an offramp from the overpass over I-88; this ramp goes around the outside of the I-88 onramp, and allows traffic to use the exit to I-290 without weaving with traffic entering from I-88. There are also two ramps that connect IL 38 from the west to I-88 from the east, via two of the stack ramps. Finally, IL 38 forms a somple half-cloverleaf giving it access to points south on I-294.

I-294 and I-88: The southern end of this interchange is nothing hugely remarkable, it's just included for completeness. A connector road connects points south on I-294 and points west on I-88, cutting off a few neighborhoods in the process. A ramp is available from the EB lanes of this connector to the local roads; its counterpart joins I-88 WB directly, and isn't visible in this photo. The connector joins I-294 just south of an absolutely massive toll plaza. There is also a folded half-cloverleaf to connect I-294 to local roads; there is no southern half to prevent traffic from getting on here to avoid the toll booth.

Comments: This interchange is certainly a contender for one of the most elongated interchanges in the country, if not the world. It was formerly known as the Hillside Strangler, because of a major bottleneck where I-88 and I-290 merged together to run into downtown Chicago; ILDoT claims to have fixed this problem, but there are some who claim they just moved it around a little. The main problem is that almost all of the traffic coming from Chicago's western suburbs comes through this interchange, and a good chunk of it heads right down I-290 into downtown; to truly avoid a bottleneck, I-290 would need as many lanes as it had to the west in addition to I-88's, giving it 8 or 9 lanes in each direction. This is obviously not feasible, so ILDoT had to do what it could to fix the problem without a gargantuan widening project. There is, however, one problem which I would fix; the ramp from I-294 NB to I-290 WB really shouldn't be a cloverleaf loop. Lots of traffic uses I-294 and I-290 to bypass the western side of Chicagoland; this movement should have some sort of flyover ramp. Space is definitely a consideration, but I believe that a simple ramp such as the one from I-294 SB to I-290 EB could be wedged in the space that the cloverleaf currently occupies. This might also allow for a straightening of the I-290 WB to I-294 ramp, taking it farther away from the adjacent residential neighborhood and allowing traffic to move along it faster.

Corrections? Suggestions? More information is always welcome.
Suggestions for more interchanges to cover on this site are great too.
Contact the author, Dan (known as DanTheMan on misc.transport.road):twowheel@email.com